JP4752234B2 - Vehicle braking force control device - Google Patents

Description

  The present invention relates to a braking force control device for a vehicle that travels by transmitting rotation from a prime mover such as an engine to drive wheels under a shift by an automatic transmission.

  As a vehicle braking force control device, for example, a device that obtains a target deceleration from a braking operation state by a brake pedal and controls the braking force of the vehicle so that the actual deceleration matches this target deceleration is known.

By the way, in addition to the deceleration due to the braking force according to the braking operation, the vehicle is also subjected to acceleration / deceleration according to the road surface gradient and deceleration due to the engine brake.
In controlling the braking force so that the actual deceleration matches the target deceleration obtained from the braking operation state as described above,
The braking force is controlled so that the acceleration / deceleration according to the road gradient and the actual deceleration including the deceleration due to engine braking match the target deceleration obtained from the braking operation state. Further, there is a problem that the acceleration / deceleration and the deceleration due to the engine brake are perceived as excessive or insufficient with respect to the deceleration expected by the own braking operation.

Therefore, according to Patent Document 1, the applicant of the present application calculates a reference deceleration corresponding to the vehicle deceleration corresponding to the road gradient or engine brake during braking of the vehicle, and calculates the difference between the actual deceleration of the vehicle and the reference deceleration. A vehicle braking force control device that controls the braking force of wheels so that the difference value matches the target deceleration has been proposed.
In this case, not the actual deceleration of the vehicle itself, but the braking force of the wheels is controlled so that what is excluded in advance from the reference deceleration matches the target deceleration. And the deceleration due to the engine brake are not felt as excessive or insufficient, and the vehicle deceleration as expected can be felt by the own braking operation, and the above-mentioned uncomfortable feeling can be eliminated.
JP 2003-170823 A

  However, it has been confirmed that the above-described braking force control causes the problems described below, for example, when a braking operation is performed such that the accelerator pedal is released and the brake pedal is stepped on immediately while the vehicle is accelerating.

FIG. 10 shows that at the instant t1, the throttle opening TVO is lowered toward the minimum opening by releasing the accelerator pedal, and at the instant t2, the master cylinder hydraulic pressure Pmc starts increasing by stepping on the brake pedal, and accordingly the vehicle speed VSP Is a time chart in the case of decreasing with a change with time in the figure.
As shown in FIG. 10, the engine torque Te starts to decrease with a high response to the decrease in the throttle opening TVO, and the automatic transmission increases as the accelerator pedal is released (throttle opening TVO decreases). The shift is started with a low response as is apparent from the change with time of the transmission gear ratio Grto.

Therefore, particularly when the brake pedal is depressed before the upshift end instant t3 (instantaneous t2), the engine torque Te is greatly reduced and the engine brake causes a large vehicle deceleration (see the time-dependent change in the vehicle acceleration / deceleration G). After the provision, the large vehicle deceleration is temporarily reduced immediately before the upshift end instant t3 as is apparent from the change with time of the vehicle acceleration / deceleration due to the upshift of the automatic transmission.
For this reason, as described above, the reference deceleration rate α _base 0 obtained from the engine torque Te and the gear ratio Grto is once decreased immediately before the upshift end instant t3 (see part A) as shown by the broken line in FIG. The actual deceleration obtained by the braking force controlled as described above based on the speed is also temporarily reduced just before the upshift end instant t3 (see section A).

Therefore, even when the braking force control technique described in Patent Document 1 is used, a braking operation such as releasing the accelerator pedal and immediately depressing the brake pedal while the vehicle is accelerating is performed. The vehicle deceleration fluctuates, causing a problem that the driver feels uncomfortable.
This problem is unavoidable even if the automatic transmission is a stepped type or a continuously variable transmission because the shift response is lower than the torque response of the engine.

The present invention is based on the fact that the above problem is caused by a change in engine braking force (reference change in deceleration) accompanying a shift of the automatic transmission during braking.
The braking force of the vehicle that eliminates the above-mentioned problems related to the fluctuation of the vehicle deceleration and eliminates the driver's uncomfortable feeling by limiting the change to a change that does not experience the change or that reduces the experience. The purpose is to propose a control device.

For this purpose, the braking force control device for a vehicle according to the present invention is configured as described below.
First of all, to explain the prerequisite braking force control device,
During braking of a vehicle that travels by transmitting the rotation from the prime mover to the drive wheels under the shift of the automatic transmission, a reference deceleration corresponding to at least the vehicle deceleration corresponding to the engine brake is calculated, and the actual deceleration of the vehicle is calculated. The wheel braking force is controlled so that the difference between the reference deceleration and the target deceleration obtained from the braking operation state matches.

The present invention provides a reference deceleration change limiting means for such a braking force control device.
The reference deceleration change limiting means obtains a reference deceleration arrival value generated by the shift of the automatic transmission during braking, and based on the reference deceleration arrival value, at least the reference deceleration corresponding to the vehicle deceleration by the engine brake. The reference deceleration change is calculated by subtracting the speed , and when the reference deceleration change is a deceleration change that can be felt by the occupant, the change in the reference deceleration is set so that the occupant does not experience the deceleration change. Limit.

In the braking force control apparatus according to the present invention, a reference deceleration arrival value generated by a shift during braking is obtained, and the reference deceleration corresponding to at least the vehicle deceleration corresponding to the engine brake is obtained from the reference deceleration arrival value. It calculates a reference deceleration changes by subtracting the reference deceleration change that the operation, when it is sensible possible deceleration change amount of the occupant, will limit the change in the reference deceleration,
During braking, the automatic transmission shifts after the high-response torque change of the prime mover (engine braking), and the reference deceleration changes due to this low-response shift, causing fluctuations in the actual deceleration. Even so, the restriction of the reference deceleration change rate is suppressed, and fluctuations in the actual deceleration that the driver feels uncomfortable can be avoided.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a power train of a vehicle having a braking force control device according to an embodiment of the present invention, and a composite brake comprising a regenerative braking device and a hydraulic brake device (friction braking device) related to the power train. Are shown together with their respective control systems.

The power train includes an engine 1, a V-belt type continuously variable transmission (may be a stepped automatic transmission) 2, and a front wheel (drive wheel) 3.
The engine 1 is a lean burnable engine, and the engine 1 is controlled by controlling the intake air amount corresponding to the throttle opening TVO determined by a throttle actuator (not shown), the fuel injection amount by the injector, and the ignition timing by the spark plug. The torque Te is controlled to match the target engine torque tTe.

The V-belt type continuously variable transmission 2 has its input shaft 4 coupled to the engine 1 via a torque converter 5 with a lock-up mechanism.
The torque converter 5 has its lock-up mechanism released at an extremely low vehicle speed range, and allows the vehicle to stop / start by increasing the torque by performing fluid transmission in the converter state in which the direct connection between the torque converter input / output elements is released. Function and torque fluctuation absorption function,
In the middle and high vehicle speed range, a lockup mechanism is fastened, and transmission is performed in a lockup state in which the torque converter input / output elements are directly connected, thereby enabling highly efficient power transmission.
The V-belt type continuously variable transmission 2 includes a primary pulley 6 coupled to an input shaft 4 and a secondary pulley 8 coupled to an output shaft 7, and a V-belt 9 is stretched between these pulleys 6 and 8. Constitute.

The V-belt type continuously variable transmission 2 is configured to wind the V-belt 9 around these pulleys by hydraulic control to narrow one pulley V-groove width of the primary pulley 6 and the secondary pulley 8 while increasing the other pulley V-groove width. The gear ratio Grto, which is the input / output pulley rotation ratio, can be changed steplessly by changing the engagement position, and the gear ratio Grto is made to coincide with the target gear ratio Gtm by such a continuously variable transmission.
Thus, the rotation from the engine 1 reaches the output shaft 7 under the continuously variable transmission by the V-belt type continuously variable transmission 2, and the rotation to the output shaft 7 is thereafter performed as a final gear set including a differential gear device (not shown). It is assumed that the vehicle reaches the front wheel 3 through 10 and can drive the vehicle.

The composite brake relating to the power train having the above-described configuration is a hydraulic brake device (friction) that generates a braking force by supplying hydraulic pressure to the wheel cylinder 11 provided in association with the front wheel 3 (only one is shown in the figure). A regenerative braking device (regenerative braking) that converts rotational energy of the vehicle power train (driving front wheels 3) into electric power by an AC synchronous motor 12 that is drivingly coupled to the input shaft 4 of the V-belt type continuously variable transmission 2 Device).
Such cooperative control of the composite brake efficiently recovers the regenerative energy by controlling the brake fluid pressure to the wheel cylinder 11 while reducing the brake fluid pressure to the wheel cylinder 11 while controlling the regenerative braking torque by the AC synchronous motor 12. This is the primary meaning.

First, a hydraulic brake device will be described. Reference numeral 13 denotes a brake pedal that is depressed according to the braking force of the vehicle desired by the driver. The pedal force of the brake pedal 13 is boosted by the hydraulic booster 14, and the boosted force When the piston cup (not shown) of the master cylinder 15 is pushed, the master cylinder 15 outputs the master cylinder hydraulic pressure Pmc corresponding to the depression force of the brake pedal 13 to the brake hydraulic pressure pipe 16.
In FIG. 1, the brake hydraulic pipe 16 is connected only to the wheel cylinder 11 provided on one drive wheel (here, the front wheel) 1, but it is also connected to the wheel cylinders related to other three wheels (not shown). It goes without saying that they are connected in the same way.

The hydraulic booster 14 and the master cylinder 15 use brake fluid in a common reservoir 17 as a working medium.
The hydraulic booster 14 includes a pump 18. The pump 18 accumulates brake fluid sucked and discharged from the reservoir 17 in the accumulator 19, and the accumulator internal pressure is sequence-controlled by the pressure switch 20.
The hydraulic booster 14 boosts the pedaling force of the brake pedal 13 using the pressure in the accumulator 19 as a pressure source, and pushes the piston cup in the master cylinder 15 with the boosted pedaling force.
At this time, the master cylinder 15 encloses the brake fluid from the reservoir 17 in the brake pipe 16 to generate a master cylinder hydraulic pressure Pmc corresponding to the brake pedal depression force, and the wheel cylinder hydraulic pressure Pwc is set to the wheel cylinder 11 The front wheel 3 can be hydraulically braked.

The wheel cylinder hydraulic pressure Pwc can be feedback controlled as will be described later using the accumulator internal pressure of the accumulator 19, so that an electromagnetic switching valve 21 is inserted in the middle of the brake pipe 16, and the wheel cylinder hydraulic pressure Pwc is higher than that of the electromagnetic switching valve 21. On the side of 11, a pressure increasing circuit 23 extending from the discharge circuit of the pump 18 and inserting a pressure increasing valve 22 and a pressure reducing valve 24 extending from the suction circuit of the pump 18 and inserted into the brake pipe 16 on the side of 11. Each of the decompression circuits 25 is connected.
The electromagnetic switching valve 21 opens the brake pipe 21 in a normal state to direct the master cylinder hydraulic pressure Pmc to the wheel cylinder 11, shuts off the brake pipe 16 when the solenoid 21a is ON, and connects the master cylinder 15 to the stroke simulator 26. Thus, according to the wheel cylinder 11, the same hydraulic load is applied, so that the brake pedal 13 can continue to be given the same operational feeling as usual.

The pressure increasing valve 22 normally opens the pressure increasing circuit 23 and increases the wheel cylinder hydraulic pressure Pwc by the internal pressure of the accumulator 19, but when the solenoid 22a is turned ON, the opening of the pressure increasing circuit 16 is decreased in proportion to the amount of current supplied. Let us reduce the pressure increase rate of the wheel cylinder hydraulic pressure Pwc,
The pressure reducing valve 24 normally shuts off the pressure reducing circuit 25. When the solenoid 24a is turned on, the pressure reducing circuit 25 increases the opening degree of the pressure reducing circuit 25 in proportion to the energization amount to increase the pressure reducing ratio of the wheel cylinder hydraulic pressure Pwc. And

Here, the pressure increasing valve 22 and the pressure reducing valve 24 shut off the corresponding pressure increasing circuit 23 and the pressure reducing circuit 25 while the switching valve 21 opens the brake pipe 16, so that the wheel cylinder hydraulic pressure Pwc is mastered. As determined by the cylinder hydraulic pressure Pmc,
Further, while the pressure increase valve 22 or the pressure reducing valve 24 is increasing or decreasing the wheel cylinder hydraulic pressure Pwc, the brake pipe 16 is shut off by turning on the switching valve 21 and is affected by the master cylinder hydraulic pressure Pmc. Without increasing the pressure, the wheel cylinder hydraulic pressure Pwc can be increased or decreased.

The switching valve 21, the pressure increasing valve 22 and the pressure reducing valve 24 are controlled by a hydraulic brake controller 27. For this reason, the controller 27 detects the master cylinder hydraulic pressure Pmc indicating the braking force of the vehicle requested by the driver. A signal from the sensor 28 and a signal from the pressure sensor 29 for detecting the wheel cylinder hydraulic pressure Pwc representing the actual value of the hydraulic braking torque are input.
Based on the input information, the hydraulic brake controller 27 controls the switching valve 21, the pressure increasing valve 22, and the pressure reducing valve 24 so that a hydraulic braking force command value described later is achieved.

The AC synchronous motor 12 that is drivingly coupled to the transmission input shaft 4 is controlled through AC / DC conversion in a DC / AC conversion current control circuit (inverter) 31 by a three-phase PWM signal from the motor torque controller 30. ,
When it is necessary to drive the wheel 3 by the motor 12, the wheel 3 is driven by the electric power from the DC battery 32,
When braking of the wheel 3 (power train) is necessary, the vehicle kinetic energy is recovered to the battery 32 by regenerative braking torque control to brake the wheel 3 (power train).
Note that a DC system in which the motor 12 is a DC motor may be used.

While communicating with the main controller 33, the hydraulic brake controller 27 and the motor torque controller 30 control the corresponding hydraulic braking device and regenerative braking device according to commands from the controller 33 as described later.
The motor torque controller 30 controls the regenerative braking torque by the motor 12 based on the regenerative braking torque command value Tmcom from the main controller 33, and controls the driving torque of the wheel 3 by the motor 12 when the driving of the wheel 3 is requested.

Further, the motor torque controller 30 calculates the allowable maximum regenerative braking torque allowed for the motor 12 determined by the state of charge of the battery 32, the temperature, etc., and transmits a signal corresponding to the main controller 33. The braking torque command value Tmcom is limited to this allowable maximum regenerative braking torque.
For this reason, in addition to inputting signals related to the master cylinder hydraulic pressure Pmc and wheel cylinder hydraulic pressure Pwc from the pressure sensors 28 and 29 via the hydraulic brake controller 27 to the main controller 33,
A signal regarding the actual gear ratio Grto from the transmission controller 37;
A signal from the wheel speed sensor 34 for detecting the wheel speed Vw of the wheel 3;
A signal from the engine rotation sensor 35 for detecting the engine speed Ne is input.

The engine 1 is controlled by the engine controller 36. The engine controller 36 determines the engine torque command value tTe from the accelerator pedal depression amount APO, mainly the throttle opening TVO electronically controlled by the throttle actuator based on this and the vehicle speed VSP. The engine 1 is controlled by the fuel injection control and ignition timing control so that the engine torque becomes the command value tTe.
The engine controller 36 communicates with the main controller 33 and transmits information on the accelerator pedal depression amount APO, the throttle opening degree TVO, and the vehicle speed VSP to the main controller 33.

  The above-mentioned shift control of the V-belt type continuously variable transmission 2 is performed by the transmission controller 37. Therefore, the transmission controller 37 basically operates the accelerator pedal depression amount APO, throttle through the main controller 33. It is assumed that the target gear ratio Gtm is obtained from information on the opening degree TVO and the vehicle speed VSP, and the above-described gear shift control is performed so that the actual gear ratio Grto matches the target gear ratio Gtm.

Based on the input information described above, the main controller 33 performs the braking force control aimed by the present invention by the processing shown in the functional block diagram of FIG. 2 and the flowcharts of FIGS.
FIG. 3 is a main routine repeatedly executed by a scheduled interrupt every 10 msec. First, in step S10, the master cylinder hydraulic pressure Pmc and the wheel cylinder hydraulic pressure Pwc of the wheel 3 are calculated.

In the next step S20, the engine speed Ne and the wheel speed Vw of the driving wheel 3 are calculated, and the latter wheel speed Vw is passed through a bandpass filter represented by the following transfer function Fbpf (s) to drive wheel deceleration. Find αv.
Fbpf (s) = s / {(1 / ω ² ) s ² + (2ζ / ω) s + 1} (1)
s: Laplace operator However, actually, it is calculated using a recurrence formula obtained by discretization by Tustin approximation or the like.

In step S30, the allowable maximum regenerative braking torque Tmmax achievable by the motor 12 and the actual gear ratio Grto of the V-belt continuously variable transmission 2 are determined from the high-speed communication reception buffer between the motor torque controller 30 and the transmission controller 37. Read.
The allowable maximum regenerative braking torque Tmmax is determined by the motor torque controller 30 according to the charging rate of the battery 32, and changes so as to increase as the vehicle speed VSP (drive wheel speed Vw) decreases.

In step S40, the target deceleration α _dem of the vehicle is calculated by the following equation using the master cylinder hydraulic pressure Pmc and a constant K1 corresponding to the vehicle specifications stored in advance in the ROM.
α _dem = Pmc × K1 (2)
Hereinafter, the deceleration is treated as a negative value, and the braking torque is treated as a negative value.
This step S40 is to obtain the target deceleration rate α _dem of the vehicle as described above, and therefore corresponds to the target deceleration calculation means 41 in FIG.

Here, the vehicle target deceleration rate α _dem is determined not only according to the master cylinder hydraulic pressure Pmc, the master cylinder stroke, or the braking physical quantity (vehicle driving state) commanded by the driver by the brake pedal depression force, but also the inter-vehicle distance. Of course, in a vehicle equipped with a control device or a vehicle speed control device, it can also be determined according to a physical quantity (vehicle running state) by automatic braking by these devices.

In step S50 of FIG. 3, a braking torque command value Tdff (braking torque feedforward compensation amount) necessary to realize the target deceleration rate α _dem is calculated using the feedforward compensator 51 of FIG. .
That is, first, the target deceleration rate α _dem is converted into a braking torque using a constant K2 determined by the vehicle specifications, and then the response characteristic Pm () of the control target vehicle 54 is converted into the characteristic Fref (s) of the reference model 52 in FIG. s) feedforward compensator for matching (phase compensator) 51 the following equation by the characteristic C _FF (s) to the target deceleration represented in (alpha _dem) corresponding target deceleration alpha for _dem through braking torque The braking torque command value Tdff (feed forward compensation amount) is obtained.
In practice, the braking torque command value Tdff (feedforward compensation amount) for the target deceleration rate α _dem is also discretized and calculated in the same manner as described above.
C _FF (s) ＝ Fref (s) / Pm (s)
= (Tp · s + 1) / (Tr · s + 1) (3)
Tp: Time constant
Tr: Time constant
Pm: Vehicle model characteristics of the controlled vehicle
(Vehicle deceleration characteristics with respect to braking torque command value)

Next, in step S60, it is determined whether or not the brake pedal has been depressed depending on whether or not the master cylinder hydraulic pressure Pmc is a minute set value or more. When this brake pedal is operated, in step S70, with obtaining the braking torque command value of the target deceleration alpha for _dem Tdfb (feedback compensation amount), finding a total braking torque command value Tdcom necessary to achieve the target deceleration alpha _dem.
In this embodiment, the deceleration controller is constituted by a “two-degree-of-freedom control system” as shown in FIG. Shall.
Closed-loop performance such as control stability and disturbance resistance is realized with the feedback compensator 53. Responsiveness to the target deceleration α _dem is basically realized with the feedforward compensator 51 (when there is no modeling error). Is done.
The first target deceleration alpha _dem is in calculating the feedback compensation amount Tdfb, obtains the reference model response deceleration alpha _ref through a reference model 52 having a characteristic Fref (s) represented by the following formula.
Fref (s) = 1 / (Tr · s + 1) (4)

Further, as shown in FIG. 5, a difference value _obtained by subtracting a corrected reference deceleration rate α _basefin described later with reference to FIG. 4 from the reference model response deceleration rate α _ref and the actual deceleration rate αv of the control target vehicle 54 (see step S20). The deceleration feedback deviation Δα between the two is obtained.
△ α = α _ref − (αv−α _basefin ) ... (5)
Then, the deceleration feedback deviation Δα is passed through a feedback compensator 53 having a characteristic C _FB (s) expressed by the following equation to obtain a braking torque feedback compensation amount Tdfb.
C _FB (s) = (Kp · s + Ki) / s (6)
However, in this embodiment, this characteristic is realized by a basic PI controller, and the control constants Kp and Ki are determined in consideration of gain margin and phase margin.
Equations (4) and (6) are calculated by discretization in the same manner as described above.

Next, as shown in FIG. 5, the braking torque command value Tdff (feedforward compensation amount) for the target deceleration α _dem described above and the braking torque feedback compensation amount Tdfb are added together to obtain a total braking torque command value (target Determine the braking torque (Tdcom).
Step S70 in FIG. 3 determines the total braking torque command value (target braking torque) Tdcom as described above, and therefore corresponds to the target braking torque calculation means 45 in FIG.

  While it is determined in step S60 that the brake pedal is not operated, in step S80, the braking torque feedback compensation amount Tdfb and the internal variable of the digital filter expressed by the equation (6) used when obtaining this are initialized to PI. The integral term of the controller is initialized, and the total braking torque command value (target braking torque) Tdcom is set to 0 in response to no brake pedal operation.

The next step S90 in FIG. 3 corresponds to the regenerative / hydraulic braking torque distribution means 46 in FIG. 2, and sets the target braking torque Tdcom obtained as described above as follows: Perform the operation to distribute to
First, the front braking torque command value Tdcomf and the rear wheel braking torque command value Tdcomr are obtained by distributing the target braking torque Tdcom back and forth based on the ideal distribution characteristic of the front and rear wheel braking torque illustrated in FIG.
The ideal distribution characteristic of the front and rear braking torque illustrated in FIG. 6 is determined by taking into consideration the prevention of rear wheel tip lock accompanying the movement of the front and rear wheel loads during braking, stability of vehicle behavior, shortening of the braking distance, and the like. This is the front / rear braking force distribution that simultaneously locks the brakes.
Since the front wheel braking torque command value Tdcomf is regeneratively braked by the AC synchronous motor 12 in addition to the front wheel 3 being hydraulically (frictionally) braked by the wheel cylinder 11 as described above with reference to FIG. Distribution calculation is performed between the torque command value Tbcomf and the regenerative braking torque command value Tmcom.

As will be described in detail below, in this embodiment, since regenerative braking is set only for the front wheels 3, the allowable maximum regenerative braking torque Tmmax obtained in step S30 is close to 0, so that substantially regenerative braking is performed. Mode 1 in which front wheel braking by means of is impossible and it is necessary to brake the front wheel only by hydraulic braking;
Mode 2 when the front wheel braking torque command value Tdcomf is larger than the allowable maximum regenerative braking torque Tmmax and the front wheels need to be braked in cooperation with regenerative braking and hydraulic braking;
Mode 3 in which the front wheel braking torque command value Tdcomf is smaller than the allowable maximum regenerative braking torque Tmmax and the front wheels can be braked only by regenerative braking;
When the maximum allowable regenerative braking torque Tmmax is large and the sum of the front wheel braking torque command value Tdcomf and the rear wheel braking torque command value Tdcomr (target braking torque Tdcom) can be provided only by the allowable maximum regenerative braking torque Tmmax, Mode 4 exists when the target braking torque Tdcom can be achieved only by regenerative braking even without hydraulic braking.

For each mode, front wheel hydraulic braking torque command value Tbcomf, rear wheel hydraulic braking torque command value Tbcomr, regenerative braking torque command value Tmcom, right front wheel hydraulic braking torque command value Tbcomfr, left front wheel hydraulic braking torque command value Tbcomfl The calculation procedure of the right rear wheel hydraulic braking torque command value Tbcomrr and the left rear wheel hydraulic braking torque command value Tbcomrl will be described.
(Mode 4) When Tmmax ≧ Tdcomf + Tdcomr: (Regenerative braking only)
Tbcomf = 0
Tbcomr = 0
Tmcom = Tdcomf + Tdcomr
Tbcomfr = 0
Tbcomfl = 0
Tbcomrr = 0
Tbcomrl = 0
(Mode 3) When Tdcomf + Tdcomr>Tmmax> Tdcomf: (Regenerative braking + Rear wheel hydraulic braking)
Tbcomf = 0
Tbcomr = Tdcomf + Tdcomr−Tmmax
Tmcom ＝ Tmmax
Tbcomfr = 0
Tbcomfl = 0
Tbcomrr = Tbcomr / 2
Tbcomrl = Tbcomr / 2
(Mode 2) When Tdcomf> Tmmax ≧ predetermined value (near zero): (regenerative braking + front and rear wheel hydraulic pressure braking)
Tbcomf ＝ Tdcomf−Tmmax
Tbcomr ＝ Tdcomr
Tmcom ＝ Tmmax
Tbcomfr = Tbcomf / 2
Tbcomfl = Tbcomf / 2
Tbcomrr = Tbcomr / 2
Tbcomrl = Tbcomr / 2
(Mode 1) Other than the above: (Front and rear wheel hydraulic braking only)
Tbcomf ＝ Tdcomf
Tbcomr ＝ Tdcomr
Tmcom = 0
Tbcomfr = Tbcomf / 2
Tbcomfl = Tbcomf / 2
Tbcomrr = Tbcomr / 2
Tbcomrl = Tbcomr / 2

In the next step S100 in FIG. 3, the vehicle parameters stored in the ROM in advance based on the hydraulic braking torque command values Tbcomfr, Tbcomfl, Tbcomrr, Tbcomrl of each wheel obtained as described above in step S90. The wheel cylinder hydraulic pressure command values Pbcomfr, Pbcomfl, Pbcomrr, Pbcomrl of each wheel are calculated by the following equation using the constant K3 based on the original.
Pbcomfr = Tbcomfr x K3
Pbcomfl = Tbcomfl x K3
Pbcomrr = Tbcomrr × K3
Pbcomrl = Tbcomrl × K3

In the next step S110, the regenerative braking torque command value Tmcom obtained as described above in step S90 is transmitted to the motor torque controller 30 in FIG. 1 (shown as the regenerative braking control means 47 including this) in FIG. 1 and output the wheel cylinder hydraulic pressure command values Pbcomfr, Pbcomfl, Pbcomrr, and Pbcomrl obtained in step S100 as the hydraulic brake controller 27 in FIG. 1 (in FIG. 2, the hydraulic braking control means 48 including this). Send to (shown) and output.
The motor torque controller 30 (regenerative braking control means 47 in FIG. 2) controls the AC synchronous motor 12 via the inverter 31 so that the regenerative braking torque command value Tmcom is achieved,
The hydraulic brake controller 27 (hydraulic braking control means 48 in FIG. 2) makes the hydraulic pressure to the front wheel cylinder 11 corresponding to the front wheel cylinder hydraulic pressure command value through the control of the solenoid valves 21, 22, 24. In addition to the control, the wheel cylinder hydraulic pressures of the other front wheel and the rear two wheels are similarly controlled to become the corresponding wheel cylinder hydraulic pressure command values.

The corrected reference deceleration rate α _basefin (see FIG. 5) necessary for obtaining the target braking torque feedback compensation amount Tdfb in step S70 of FIG. 3 is obtained as follows by the subroutine shown in FIG.
In step S701, the standard deceleration rate α _base 0 corresponding to the vehicle deceleration corresponding to the engine brake is calculated from the engine torque Te that can be estimated from the engine speed Ne, the throttle opening TVO, and the like, and the actual gear ratio Grto. Estimated by calculating the formula.
α _base 0 ＝ Te × Grto × Gf / Rt / M (7)
However, Gf: Final gear ratio
Rt: Effective tire radius
M: Vehicle mass The reference deceleration α _base 0 is made to correspond only to the vehicle deceleration corresponding to the engine brake here, but it can also correspond to the vehicle deceleration equivalent to the road surface gradient.
As described above, step S701 is to obtain the reference deceleration rate α _base 0 and corresponds to the reference deceleration calculation means 42 in FIG.

In the next step S702, the reference deceleration alpha _base 0 of the comparison that the previous value alpha _base 0 (previous value), and determines whether the α _base 0 ≦ α _base 0 (previous value).
While it is determined that α _base 0 ≤ α _base 0 (previous value), that is, while the negative reference deceleration α _base 0 is increased in absolute value (while the reference deceleration is large) Since the present invention described above with reference to FIG. 10 does not cause a problem, the control proceeds to step S703 and step S704.
In step S703, the corrected reference deceleration rate α _basefin is set to the same value as the reference deceleration rate α _base 0 obtained in step S701, and this is corrected without any restriction on the reference deceleration rate α _base 0. The speed α _basefin is used for the calculation in step S70 of FIG.
In step S704, the reference deceleration limit flag _fbaseimt is _set to 0 to indicate that the reference deceleration α _base 0 is not limited.

While the comparison result between the reference deceleration α _base 0 and its previous value α _base 0 (previous value) is determined as α _base 0> α _base 0 (previous value) in step S702, that is, a negative value reference While the deceleration α _base 0 is being reduced in absolute value (while the reference deceleration is small), there is a risk that the present invention described above with reference to FIG. Proceed to S705.
In this step S705, it is checked whether or not the reference deceleration rate α _base 0 is already limited depending on whether or not the reference deceleration limit flag f _baselmt is 1.
When determining still limits the reference deceleration alpha _base 0 is not performed and _(f baselmt = 0) in step S706~ step S 708, the following whether to perform the restriction of the reference deceleration alpha _base 0 to decide.

In step S706, when the upshift corresponding to the vehicle deceleration corresponding to the engine brake caused by the upshift of the continuously variable transmission 2 from the present time by releasing the foot from the accelerator pedal and moving it onto the brake pedal. The reference deceleration arrival value α _basestc is estimated and calculated by the following equation.
α _basestc = Te x Grtoh x Gf / Rt / M (8)
However, Grtoh: using the minimum value in the next step S707, the reference deceleration alpha _base 0 determined in this upshift reference deceleration value to be reached alpha _Basestc and step S701 of the gear ratio to be achieved by the upshift, the A reference deceleration change (decrease) amount α _{basedlt due} to _upshift is calculated by the following equation.
α _basedlt = α _basestc −α _base 0 (9)
As described above, step S707 calculates the reference deceleration change (decrease) amount α _basedlt and corresponds to the reference deceleration change amount calculation means 43 in FIG.

In step S708, the reference deceleration change (decrease) amount α _basedlt is experienced depending on whether or not the reference deceleration change (decrease) amount α _basedlt due to the _upshift is equal to or greater than the _perceivable deceleration change amount determination value α _basejdg. Check if it is something like this.
When it is determined in step S708 that α _basedlt <α _basejdg , the reference deceleration change (decrease) amount α _basedlt is not large enough to be experienced, and the problem to be solved by the present invention does not occur. Then, the control proceeds to step S703 and step S704 described above.
When it is determined in step S708 that α _basedlt ≧ α _basejdg , the reference deceleration change (decrease) amount α _basedlt is large enough to be experienced, and the problem to be solved by the present invention arises. First, in step S709, the reference deceleration limit flag f _baselmt is set to 1 to indicate that the reference deceleration α _base 0 is restricted in the subsequent steps S710 to S712.

Since the reference deceleration limit flag _fbaselmt is set to 1 in step S709 as described above, step S705 skips steps S706 to S709 and advances the control to step S710. The process in step S709 is executed only once at the beginning when step S702 determines that α _base 0> α _base 0 (previous value).

In step S710, the limit value (reference deceleration limit value) α _baselmt for the reference deceleration α _base 0 is set so that the reference deceleration change (decrease) amount α _basedlt is not experienced. Obtained as follows.
First, based on the map illustrated in FIG. 7, the master cylinder hydraulic pressure Pmc (the braking operation status by the driver is not limited to the master cylinder hydraulic pressure Pmc, but may be other braking physical quantities such as a master cylinder stroke and a brake pedal depression force). ), A change limit value (reference deceleration change rate limit value) α _dltlmt for the reference deceleration α _base 0 per calculation cycle is obtained.
This reference deceleration change rate limit value α _dltlmt is for making the reference deceleration change (decrease) amount α _basedlt small outside the sensation range. As shown in FIG. 7, the master cylinder hydraulic pressure Pmc is When the value is in the normal range below the set hydraulic pressure Pmclmt (when the value is in the master cylinder hydraulic pressure region generated during general braking excluding sudden deceleration), the lower limit of the rate of change in deceleration that can be experienced in light of the purpose The minimum value α _dltmin smaller than the value is set.
However, if the master cylinder hydraulic pressure Pmc is greater than or equal to the set hydraulic pressure Pmclmt, the reference deceleration change rate limit value α _dltlmt is obtained as the master cylinder hydraulic pressure Pmc rises in order to obtain the effect described in detail later. It is increased from the minimum value of α _dltmin to relax the restriction on the change in reference deceleration.

In step S710, the following formula is added to the corrected reference deceleration rate α _basefin (previous value) previously determined in step S712 and the reference deceleration change rate limit value α _dltlmt determined as described above α _baselmt = α _basefin (previous time) Value) + α _dltlmt (10)
Based on the above calculation, a reference deceleration limit value α _baselmt for _{preventing the} change in the reference deceleration from being experienced is obtained.

In the next step S711, the reference deceleration limit value α _baselmt is compared with the reference deceleration α _base 0 obtained in step S701 to check whether α _baselmt ≦ α _base 0.
When it is determined in this step S711 that α _baselmt ≦ α _base 0 is not _satisfied , the control described above with respect to FIG. 10 does not cause a problem even if the reference deceleration rate α _base 0 is not corrected (change limitation). the advances to step S703 and step S704, and sets the reference deceleration alpha _base 0 to the corrected reference deceleration alpha _Basefin in step S703, to indicate that not subjected to restriction of the reference deceleration alpha _base 0 in step S704 _{Set the} standard deceleration limit flag f _baseimt to 0.

When it is determined in step S711 that α _baselmt ≦ α _base 0, if the reference deceleration rate α _base 0 is not corrected (change restriction), the above-described problem arises that the present invention solves with respect to FIG. in correcting the reference deceleration alpha _base 0 to be eliminated (change restriction) Subeku step S712, it sets the reference deceleration limit value alpha _Baselmt instead of the corrected reference deceleration reference deceleration degree _α basefin α _base 0.
Step S712 corrects (changes limit) the reference deceleration α _base 0 as described above, and therefore corresponds to the reference deceleration change limiting means 44 in FIG.

The operational effects of the above-described embodiment will be described below with reference to FIG.
FIG. 8 shows an operation time chart of the present embodiment under the same conditions as in FIG. 10, and at the instant t1, the throttle opening TVO is lowered to the minimum opening by releasing the accelerator pedal, and the upshift accompanying this is finished. FIG. 5 is a time chart when the master cylinder hydraulic pressure Pmc starts to increase due to the depression of the brake pedal at an instant t2 before the instant t3.

In the present embodiment, a reference deceleration change amount α _basedlt generated by a shift during braking (upshift where the gear ratio Grto becomes small) after the instant t2 is estimated (step S707), and the estimated reference deceleration change amount is estimated. alpha _Basedlt is, (when determined that _α basedlt ≧ α basejdg in step S708) when determined that the experience possible deceleration change amount of the occupant, the change rate of the reference deceleration alpha _base 0 is limited to alpha _Dltlmt Since the obtained corrected reference deceleration rate α _basefin is used as the reference deceleration rate α _base 0 (step S712),
That is, in detail based on FIG. 8, conventionally, even if the reference deceleration change amount α _basedlt generated by the shifting (upshift) during braking is the deceleration change amount that can be experienced by the occupant, the reference deceleration rate α _base to 0 had been used as without correcting as indicated by the thin broken line in part B, in the present embodiment, instead of the reference deceleration alpha _base 0, the change rate of the reference deceleration _{α base} 0 α dltlmt Because the corrected reference deceleration rate α _basefin obtained by limiting to is used as shown by the thick broken line in B part,
The automatic transmission shifts (upshift) after the high-response torque change of the engine (engine braking) that occurs before the instant t2, and this low-response shift (upshift) causes a reference deceleration. Even if α _base 0 changes as shown by a thin broken line at B part and causes fluctuation of actual deceleration as shown by a thin solid line at B part, thick suppressed as indicated with broken lines smooth ones without a as shown actual deceleration by the thick solid line in part B, it is possible to avoid the fluctuation of the actual deceleration the driver thinks the discomfort.

Further, in this embodiment, as illustrated in FIG. 7, the reference deceleration rate change rate limit value α _dltlmt is set to the minimum value α _{dltmin at} which the limit of the reference deceleration change rate is the strongest in the normal range of the master cylinder hydraulic pressure Pmc. However, when the master cylinder hydraulic pressure Pmc increases (the greater the brake is) during large braking operations such as sudden braking, the reference deceleration rate change rate limit value α _dltlmt is set to gradually increase from the minimum value α _dltmin. Since the limitation on the deceleration change rate is gradually reduced, the following effects can be obtained.
In other words, since the braking operation force is small and the vehicle deceleration is small in the normal range of the master cylinder hydraulic pressure Pmc, the driver can easily experience the deceleration change accompanying the shift after engine torque change (engine brake generation) during braking. But,
In this embodiment, since the limit value α _dltlmt of the reference deceleration change rate is set to the lowest value α _dltmin that is the strongest in the normal range of the master cylinder hydraulic pressure Pmc, after the engine torque change during braking (engine brake generation) As described above with reference to FIG. 8, the change in deceleration accompanying the shifting of the vehicle is reliably mitigated, so that the driver can not feel it.

On the other hand, the master cylinder hydraulic pressure Pmc is corrected if the limit value α _dltlmt of the reference deceleration change rate _remains at the minimum value α _dltmin even during large braking when the master cylinder hydraulic pressure Pmc is higher than the normal range as shown by ΔPmc. The base deceleration α _basefin and actual deceleration are shown by thin broken _lines and thin solid _{lines in} part C of the same figure respectively. As a result, a large vehicle deceleration is maintained over a long period of time, and it is easy to cause a braking lock on the wheel. , Rock tends to be deeper.
Such a phenomenon becomes more prominent as the master cylinder hydraulic pressure Pmc increases.
On the other hand, when the master cylinder hydraulic pressure Pmc exceeds the normal range as in the present embodiment, the higher the master cylinder hydraulic pressure (the greater the braking), the higher the limit value of the reference deceleration change rate. When α _dltlmt is set to gradually increase from the minimum value α _dltmin and the limit of the reference deceleration change rate is set to gradually decrease, the corrected reference deceleration α _basefin and actual deceleration are shown in part C of Fig. 9, respectively. As indicated by a thick broken line and a thick solid line, the above-described problem that the braking lock of the wheel is likely to occur and the problem that the lock tends to become deep can be solved.

Although not clearly shown in the illustrated example, the driver requests a change in deceleration to switch the selection range of the automatic transmission to a range where the engine brake is more effective, or conversely, the selection range of the automatic transmission is changed to that of the engine brake. When switching to a range where the effect becomes small, it is possible to prohibit the restriction of the reference deceleration change rate.
Such automatic transmission selection range switching means a driver's intentional change in deceleration. In this case as well, if the rate of change in the reference deceleration is continued, the driver feels a delay in the response of the deceleration. However, when the restriction of the reference deceleration change rate is prohibited at the time of switching the selection range as in this embodiment, it is possible to realize braking that does not give the driver a sense of delay in response to the deceleration change request.

  In any of the above-described embodiments, the case where the V-belt continuously variable transmission 2 is used as the automatic transmission has been described. However, the present invention is not limited to other types of toroidal continuously variable transmissions, It goes without saying that not only the step transmission but also a stepped automatic transmission can be similarly applied to achieve the same effect.

1 is a schematic system diagram showing a power train of a vehicle including a braking force control device according to an embodiment of the present invention, and a regenerative braking device and a hydraulic unit related to the vehicle, together with respective control systems. It is a block diagram according to function which shows the control content of the braking force control which the main controller in the control system performs. It is a flowchart which shows the main routine of the braking force control program which the main controller performs. It is a flowchart which shows the subroutine regarding the calculation process of the corrected reference deceleration used in the total braking torque command value calculation process in the main routine. It is a block diagram which illustrates the deceleration controller of a vehicle. It is a characteristic view which illustrates the front-and-rear wheel braking torque ideal distribution characteristic of vehicles. It is a characteristic diagram regarding the limit value of the standard deceleration change rate. It is an operation | movement time chart of the braking force control apparatus shown in FIGS. 5 is an operation time chart of the braking force control apparatus shown in FIGS. It is an operation | movement time chart of the conventional braking force control apparatus.

Explanation of symbols

1 engine (motor)
2 V belt type continuously variable transmission (automatic transmission)
3 Front wheels (drive wheels)
4 Transmission input shaft 5 Torque converter with lock-up mechanism 6 Primary pulley 7 Transmission output shaft 8 Secondary pulley 9 V belt
10 Final gear set
11 Wheel cylinder
12 AC synchronous motor
13 Brake pedal
14 Hydraulic booster
15 Master cylinder
16 Brake hydraulic piping
17 Reservoir
18 Pump
19 Accumulator
20 Pressure switch
21 Solenoid switching valve
22 Booster valve
23 Booster circuit
24 Pressure reducing valve
25 Pressure reducing circuit
26 Stroke simulator
27 Hydraulic brake controller
28,29 Pressure sensor
30 Motor torque controller
31 DC / AC conversion current control circuit (inverter)
32 DC battery
33 Main controller
34 Wheel speed sensor
35 Engine rotation sensor
36 Engine controller
37 Transmission controller
41 Target deceleration calculation means
42 Reference deceleration calculation means
43 Reference deceleration change calculation means
44 Reference deceleration change limiting means
45 Target braking torque calculation means
46 Regenerative / hydraulic braking torque distribution means
47 Regenerative braking control means
48 Hydraulic braking control means
51 Feedforward compensator
52 Reference model
53 Feedback compensator
54 Vehicles to be controlled

Claims (4)

Used in vehicles that travel by transmitting the rotation from the prime mover to the drive wheels under the shift of the automatic transmission,
During braking of the vehicle, a reference deceleration corresponding to at least the vehicle deceleration corresponding to the engine brake is calculated, and a difference value between the actual deceleration of the vehicle and the reference deceleration is a target obtained from the braking operation state. In a vehicle braking force control device for controlling the braking force of a wheel so as to coincide with a deceleration,
A reference deceleration arrival value generated by the shift of the automatic transmission during braking is obtained, and a reference deceleration is subtracted from the reference deceleration arrival value corresponding to at least the vehicle deceleration corresponding to the engine brake. It calculates the deceleration change,
When the reference deceleration change is a deceleration change that can be felt by the occupant, the vehicle is provided with reference deceleration change limiting means for limiting the change in the reference deceleration so that the occupant does not experience the deceleration change. A braking force control device for a vehicle. The braking force control apparatus for a vehicle according to claim 1,
The vehicle braking force control device according to claim 1, wherein the reference deceleration change limiting means increases the limitation of the reference deceleration change as the braking operation is large. The vehicle braking force control device according to claim 1 or 2,
The vehicle braking force control device according to claim 1, wherein the reference deceleration change limiting means prohibits restriction of the reference deceleration change when the selection range of the automatic transmission is switched. The vehicle braking force control device according to any one of claims 1 to 3,
A reference deceleration arrival value generated by the shift of the automatic transmission during braking is obtained, and a reference deceleration is subtracted from the reference deceleration arrival value corresponding to at least the vehicle deceleration corresponding to the engine brake. A reference deceleration change amount calculating means for calculating a deceleration change amount;
A reference deceleration change amount determining means for checking whether or not the reference deceleration change amount calculated by this means is a deceleration change amount that can be sensed by the occupant,
The reference deceleration change limiting means is configured so that the reference deceleration change amount determining means determines that the reference deceleration change amount is a perceivable deceleration change amount so that the passenger does not experience the deceleration change. A braking force control apparatus for a vehicle, characterized by limiting a rate of change in speed .

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